Fiber gear



April 23, 1935. J, c( SHERMAN 1,999,062

FIBER GEAR Filed Aug. 23, 1952 Patented Apr. 23, 1935 I l 'i 1,999,062

UNITED STAT-Es PATENT OFFICE.'

FIBER GEAR John C. Sherman,Gorham, Maine, assignor to Brown Company, Berlin, N. H., a corporation of Maine l Application August 2s, 1932, serial No. stoms` '3 Claims.. (Cl. 'i4-445) This invention relates to the manufacture of Inthis respect, refined wood pulp diners markedly so-called fiber gears, such as are frequently used from the-ordinary wood pulps, which, in the pres- When smooth and quiet performance is desired. ence of water, tend to generate mucilaginous hy- In making such gears, it is sometimes the practice drates which detract from the porosity and ab- 5 to build up the gear blanks from plies of woven sol'bency of webs made therefrom,l even when 5 fabric, such as canvas, impregnated with suitable Such ordinary wood pulps are used in substanarticial resinous binders. One of the principal tially unbeaten condition. So, too, I handle my items of expense in such gears is the fabric base, rened Wood pulp on the papermaking machine which, however, has heretofore been found to be in a Way quite differentfrcnl Ordinary papelan essential element in yielding an article of the making Practice. Thus, I deDcSit the rened l0 desired strength, especially resistance to shock. WOOd Pulp berS in their free, Substantially un- I have found that a rened or purled wood beaten condition on the usual wire clothor screen pulp of high alpha cellulose content may be ad- 0f the Paperrnaking machine into a Web Which iS vantageously used in an unwoven, comparatively dewatered and dried Without being subjected to inexpensive form as the fibrous base in gears of the heavy pressures usually exerted on the web 15 the foregoing type, namely, in the form of a preby squeeze rolls or the like. As a result of such fabricated web of interfelted bers of such high practice, I Secure a fiuiy Web cOlnPOSed 0f 100Sely porosity and absorptivity that it can be easily and felted bers and characterized by its extraordiperfectly impregnated throughout with the nary softness, porosity, and abserptivity.

proper articial resinous binder and then be plied On the accompanying drawing, Figures 1 y t0 2U into a structure of the desired thickness. 4, inclusive, show in perspective the various It is essential that the pulp serving the purstages of gear manufacture, beginning with an pose of the present invention be one refined to unimpregnated disk of the interfelted wood pulp high alpha cellulose content, as the ordinary and ending With a finished gear.

wood pulps, such as sulphite and kraft, do not The dry, water-laid web may be died-out or 25 possess the desired absorbency or other charcut into disks which are to be impregnated and acteristics requisite to the securement of my base to constitute the plies cf gear blanks- A disk web. `such wood pulps as I employ as raw main its unimpregnated and impregnated State iS terial are those which are arrived at only by ren shown in Figures 1 and 2, respectively, a fraging the ordinary wood pulps to an alpha cellulose mentofthe disk being breken away for the sake :no

content of at least about 93%, as by the reaction of clearer illustration. The. disks may be imthereupon of caustic soda solutions or other alka- Dregnated with the desired,- artificial reSinOuS line liquors under special conditions, as now .binder 0f the nature 0f bakelite- FOr example, Well-known in the pulpmaking industry. The they may be dipped into a 10% to 20% solution refined wood pulp is thus largely freed from less of a bakelite varnish of about'60% solids conresistant cellulose, ligneous matter, resins, and tent in a Suitable SOlvent 0r thinner- At this other non-alpha cellulose components, which not concentration, the bakelite solution'is thin and only detract from its quality of ahsorbency but easy-flowing so -that upon remaining immersed render it unstable especially under the action of in the Scluticn'fOr abcut One-half t0 One minute,

4o heat. the disks become thoroughly impregnated with 4" The base web or felt answering my purposes the solution. They may then be squeezed to a iS prepared in such a way that it possesses bakelite solids content of, say, about 50%, based A maximum porosity and absorbency. This means 0n the Weight 0f dry ber- The impregnated that I depart from conventional papermakingdisks may then be superposed into gear blanks practice in fabricating the web. Indeed, rather of the desired thickness, which may be vair-dried 4 than beating or hydrating the refined wood pulp under heavy compression; and, when an air-dryto a marked degree, as is done in conventional ing bakelite Varnishl iS emplclled, n0 heat treatpapermaking practice, I employ a suspension of ment of the dried blanks is necessary. A gear substantially unbeaten or unhydrated relined blank of the desired character is illustrated in r wood pulp as the stock being sluiced. to the'head- Figure 3. this blank being 0f cylindrical form and 0 box of thel paperrnaking machine. 'Ihe refined designed more especially for cutting or shaping wood pulp can be handled in the form of an into a spurgear. If an intermediate type of aqueous suspension without losing to any notebakelite varnish is used, the dried blanks worthy extent` its free` condition, that is its should be heated or cured to render the varnish r freedom from gelatinized or hydrated cellulose. infusiblc and insoluble and to impart other desired characteristics thereto, The heat treatment or curing may be performed at a temperature and for a period of time consonant with the hardness desired in the nished article. For instance, curing may be carried out in a press at a temperature of, say, 4135" C. for Aabout 90 minutes, under which conditions the plies become tenaciously bonded together and acquire the hardness and hornlike toughness value in liber gears.

Blanks produced in accordance with the foregoing method may undergo machining in the ordinary gear-shaping or gear-generating machines and be otherwise processed by the usual machines employed in connection with metal gear blanks. For instance, the blank may be shaped and iinished into a spur gear having the conventional form depicted in Figure 4. The finished gears` are characterized by their homogeneity of structure and the excellent resistance lto shattering impact that comes with no local weak spots. It is by virtue of the character of the fiber used as raw material and of the web formed therefrom that the gears possess these desired properties, for, if it be attempted to use ordinary paper webs, for instance, papers made from evenhigh grade rags, as a material of construction for the gears, it is found that the gears are not proof against fracture and that they fail badly under the stresses of use.

The manufacturing steps hereinbefore given are subject to considerable variation, but in any event the basic web should be made as hereinbefore described. As one possible modification, it might be mentioned that the disks for building up the gear blanks may be died-out or cut from a web which has previously -undergone impregnation with the desired artificial resinous binder. Thus, the web as it comes in dry condition from the web-forming machine may be impregnated with a bakelite varnish of the intermediate type, then dried, and, if desired, accumulated as rolls. Disks of the desired size may then be died-out or cut from the impregnated sheet, stacked into gear blanks of the desired thickness, and the blanks compressed at elevated temperature to cause their plies to unite as well as to transform the bakelite to the desired hard, non-frangible, insoluble and infusible condition.

The term bakelite is used in the foregoing description and in the appended claims in its comprehensive' sense to include the various phenol and/or aldehydic or other articial resinous condensation products, which, in their ultimate or cured condition, are comparatively hard, non-frangible, insoluble, and infusible.

I claim:

1. A gear made up of compressed, plied, waterlaid webs of loosely felted wood pulp having an alpha cellulose content of at least about 93% and impregnated substantially uniformly throughout and bonded together with an artificial, resinous binder of the nature of bakelite.

2. A gear made up of compressed, plied, waterlaid webs of loosely felted, substantially unbeaten, cellulose pulp having an alpha cellulose content of at least about 93% and impregnated substantially uniformly throughout and bonded together with a cured, artiiicial, resinous binder of the nature of bakelite.

3. A gear made up of compressed, plied, waterlaid webs of loosely felted, substantially unbeaten, wood pulp having an alpha cellulose content of at least about 93% and impregnated substantially uniformly throughout and bonded together with a cured, articial, resinous binder of the nature of bakelite in the amount of about 50% by weight of the pulp.

4. A gear made up of plied, waterlaid webs of substantially unhydrated, interfelted cellulose liber of high alpha cellulose content and in themf said gear structure highly resistant to shattering upon impact and to the stresses of use.

6,. A gear made up of compressed, plied, waterlaid webs of loosely felted cellulose pulp having' an alpha cellulose content of at least about 93% and impregnated substantially uniformly throughout and bonded together with. a binder imparting thereto the qualities of hardness and hornlike toughness.

7. A gear made up of compressed, plied, waterlaid webs of felted, substantially unbeaten wood pulp having an alpha cellulose content of at least about 93% and impregnated substantially throughout and bonded together with a binder imparting thereto the qualities of hardness and hornlike toughness.

JOHN C. SHERMAN. 

